This invention relates to a method and apparatus for driving a pile into the ground.
There have hitherto been known a first method of driving a pile into the earth or ground by striking it by means of a hammer and a second method of driving a hollow pile by eliminating the soil therein by excavation by using an auger etc.
The first pile driving method is advantageous in that its work execution cost is low, but is disadvantageous in that it will accompany increased vibration and high level noise caused thereby.
Whilst, the second pile driving method is advantageous in that the vibration and noise created during the execution thereof can be reduced, but is disadvantageous in that the rate of execution of work becomes low thereby increasing the work execution cost.
Stating in more detail, the second pile driving method comprises placing an auger inside a hollow pile and rotating the auger so as to excavate the earth in the leading end of the pile and remove the excavated earth therefrom thereby enabling the pile to be driven successively into the earth. Therefore, it is required to remove and lift the excavated soil from the lower part of the hollow pile to the upper part thereof by means of an auger having a length approximately equal to the pile to be driven. Accordingly, the longer the pile to be driven in the earth, the longer the auger to be used and the distance along which the excavated earth and sand are carried, and larger the auger torque.
As a result, the auger cannot be rotated at high speed and so the excavated earth and sand removing speed will become low and consequently the pile driving speed will become low thereby increasing the work execution cost.
In order to increase the rate of removal of excavated earth and sand, the speed of rotation of the auger has to be increased. In such a case, however, provision of a high horse power electric motor is required and the torque created thereby will increase and therefore there is a risk that a body to support the motor may upset.